The surface of human skin is protected by stratum corneum. Among the constituents of stratum corneum, stratum corneum intercellular lipid forms a lamella structure and contributes to maintain skin's basic function.
The stratum corneum intercellular lipid consists of ceramide, cholesterol, free fatty acid and the like. Among them, the ceramide is a main component and plays a central role in moisture retention and barrier function of the stratum corneum. It is known that if the content of ceramide in the stratum corneum is reduced, the protective barrier function of the stratum corneum is reduced and various skin diseases are exacerbated.
Meanwhile, it has been reported that if the stratum corneum is damaged by skin aging or external stimuli and thus the content of ceramide in the stratum corneum is reduced, the skin's lamella structure can be restored by supplementing ceramide from the outside and thus the skin can be restored to its normal state. Accordingly, for the purpose of restoring and maintaining skin barrier function and enhancing moisturizing power, the development of cosmetic composition containing the ceramide is actively being done.
The ceramide is extracted from various plants and animals containing the ceramide. However, the natural ceramide is not suitable for commercialization because it is difficult to mass-produce and the raw material is expensive due to difficulty of extraction and the like. In addition, the natural ceramide is low in solubility in various solvents used in cosmetics, and thus the natural ceramide is limited in the amount that can be used when preparing a product and there is a limit to obtaining efficacy.
Therefore, in order to replace the natural ceramide, it is necessary to research and develop a pseudo-ceramide compound which has a structure similar to the natural ceramide, is easy to synthesize, and has improved physical properties.